High pressure pulverized coal gasifier



Jan. 23, 1962 A. B. STEEVER 3,018,174

HIGH PRESSURE PULVERIZED com. GASIFIER Filed July 21, 1958 3 ets-Sheet 1 FIG. 1A

141 INVENTOR.

Andrew B. Sreever fim ATTORNEY Jan. 23, 1962 A. B. STEEVER 3,018,174

HIGH PRESSURE PULVERIZED COAL GASIFIER Filed July 21, 1958 5 Sheets-Sheet 2 Jan. 23, 1962 A. B. STEEVER HIGH PRESSURE PULVERIZED COAL GASIFIER 3 Sheets-Sheet 3 Filed July 21, 1958 INVENTOR. Andrew B. Sreever AT TORNEY hired States Patent Ofiice dflidjtl'd Patented den. 23, 19%2 3,018,174 HIGH PRESSURE PULVERFZED COAL GAdlFiER Andrew B. Steever, Said Greenwich, Conn, assignor to The Babcoch & Wiicox Company, New York, N.Y., a corporation of New Eersey Filed Finally 21, 1958, Ser. No. 749,999 8 Ciairns. ((Il. 48-63) This invention relates to the production of synthesis gas by the reaction of pulverized carbonaceous fuel, gas, and steam and, more particularly, to a novel superatmospheric pressure gasifier or reactor, for producing the synthesis gas, and associated pressurized fuel feeding and gas receiving components.

The fundamental principles involved in reacting coal with oxygen and steam, to produce a synthesis gas comprising essentially H and CO, are well-known, this reaction customarily designated as coal gasification. Briefly, the fundamental process involves a high temperature exothermic reaction of coal, steam, and a quantity of oxygen insufiicient for complete combustion of the coal. The coal and oxygen react to produce CO which, in an endothermic reaction with the carbon particles, is substantially all converted to CO. The steam, by dissociation and reaction, produces H so that the product gas is essentially H and CO. This product gas may be utilized in known procedures for producing hydrocarbons.

The use of coal in the pulverulent or pulverized form has known advantages in a coal gasification process but introduces problems relative to slag tapping and dwell time in the reactor. In US. Patent No. 2,801,158, issued in the names of P. R. Grossman and T. S. Sprague on July 30, 1957, there is shown, described and claimed a novel two-Zone gasification method and apparatus using pulverized coal, and providing for adequate dwell time for substantially complete gasification as well 'as for continuous tapping of molten slag. The Grossman et a1 method and apparatus effect gasification at essentially atmospheric pressure.

When the synthesis gas is produced at substantially atmospheric pressure, additional equipment must be pro vided to raise the pressure to a higher value for subsequent processing of the gas. Such compressing equipment could be eliminated, or at least substantially reduced in size and cost, if the synthesis gas were produced at a suitable superatmospheric pressure. This could be effected by introducing all the initial reactants at such superatmospheric pressure, which would be desirable as the size and cost of equipment for raising the pressure of the initial reactants would be a fraction of the size and cost of equipment for raising the pressure of the synthesis gas produced, due to the very small volume of the initial reactants as compared with the much larger volume of the product gas.

The present invention is directed to a novel combination and interaction of components for delivering the reactants to the gasifier at a selected atmospheric pressure, continuously tapping slag at such pressure, Washing the synthesis gas, and conserving re-useable materials, such as water and inert gas, used in the process or as auxiliaries thereto.

More particularly, the apparatus of the invention includes a two-zone gasifier or reactor, basically of the type disclosed and claimed in said Grossman et al. patent but including novel features especially adapting it to superatmospheric pressure operation. The gasifier is enclosed in an enlongated cylindrical upright metal shell protected against excessive temperatures by a cylindrical water wall of upright tubes sealed to each other, with the "annular space between the Water wall and the casing receiving a pressure equalizing blanket of saturated steam. The shell also encloses a slag tank or receiver disposed below the water-wall-confined reaction chamber.

The solid reactants, such as pulverized coal, are fed to the reaction chamber by a novel pressurized feeding system involving lock hoppers interposed between a pulverized coal surge bin and a coal feeder. in the lock hoppers, the pulverized coal is pressurized by an inert gas, such as carbon dioxide or nitrogen from a source of gas having a pressure substantially above the operating pressure of the reactor, in order to pressurize the voids in the coal. While either carbon dioxide or nitrogen may be used as the pressurizing inert gas, carbon dioxide is preferable as it will react with the coal in the reactor whereas nitrogen will be a thermal loss even though nitrogen may eventually be needed if ammonia is to be produced from the synthesis gas. Novel interlocking valve arrangements are provided between the hoppers and between the upper hopper and the surge bin, including means for providing puffs of inert gas to the valve seats to clean the same before closure. Blowdown receivers and pumping apparatus are provided for conserving and re-using at least the major part of the inert gas used for pressurizing. A novel feature is the provision of a pressure equalizer connection between the outlet of the coal feeder and the space above the coal in the lower pressure tank or hopper.

The pulverized coal is carried to paired burners in the reaction unit by means of reaction steam. Preferably, a pair of feeders are provided operating independently of each other at about one-half load, this feature providing for continuity of operation should one or the other of the feeders be out of service. The two streams of coal are joined beyond the feeders into a common coal-steam line which is later divided with a coal splitter into two lines leading to the burners in order that equal amounts of coal and steam will be delivered to the two burners irrespective of the number of feeders in operation or the rate of feeding.

The oxygen, required in the gasification process, is not premixed with the coal and steam but is delivered to the reaction chamber at or adjacent the exit of the coalsteam burners. Water jacketed burners are used and, to avoid condensation of the reaction steam, circulating saturated water from the gasifier water wall is used to cool the burners.

The slag is tapped into a double lock hopper system wherein the hopper or let-down tank continually receives slag sluiced from the slag receiver. At periodic intervals the slag is transferred by gravity and siuicing to a lower let-down tank where it is depressurized and sluiced to disposal. Most of the sluicing water is re-circulated to save pumping costs, and the molten slag is cooled by blowing down some of the recirculated water.

The raw synthesis gas leaving the gas generator or reactor is fed through a gas scrubber using a wet method to remove a very large portion of the solid residue in the synthesis gas. This scrubber also uses water at the saturation temperature of the gas.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings. In the drawings:

FIGS. 1A and 1B, in combination, present a part elevation, part vertical sectional, and part schematic View of a synthesis gas producing plant embodyin the invention, the reactor being shown in axial section;

FIG. 2 is a partial plan view of the plant;

FIG. 3 is an enlarged sectional view of a burner nozzle for introducing the reactants into the reactor;

FIG. 4 is an enlarged partial axial view of the lower portion of the reactor; and

FIG. 5 is a vertical sectional view through a pressure sealed coal feeding valve.

Referring to FIGS. 1 and 2, the reactor comprises a reaction chamber 30 which is enclosed within an elongated cylindrical shell 11 having a dome shaped head 12 secured in pressure-tight relation to its upper end and having a flanged outlet 13 in its lower end. Reactor 3%) is disposed Within the enclosure formed by a circular cross-section row of upright tubes sealed to each other to form a water wall 14 within and spaced from shell 11 to form an annular space 15. The water wall tubes extend between a lower annular header 16 and an upper annular header 17. Shell 11 is covered with an external layer of insulation 19.

Water wall 14 and annular space are in communication with a steam and water drum 20 mounted above and to one side of shell 11 on the structural framework supporting the apparatus, generally indicated at 13. Make-up connection 21 extends from the water space of drum 29 into shell 11, communicating with lower annular header 16. A connection 22 supplies water to nozzles 25 arranged around the periphery of water wall 14 just above reaction chamber 30. A riser 23 connects upper annular header 17 to drum 20, which latter mal be equipped with steam and water separating means.

Saturated steam from the steam space of drum 20 is delivered to annular space 15 by a saturated steam line 24. The saturated steam blanked in space 15, in cooperation with water wall 14, protects shell 11 against excessive temperature, the stern in space 15 acting as a pressure equalizing steam blanket. This steam is delivered to the product gas stream by a connection 26 at the top of space 15. Since, in a water gas shift process, steam is required, there is no steam loss other than condensation on the inner surface of shell 11 and the steam blanket in space 15 promotes uniform temperature of pressure shell 11. A condensate outlet 27 is provided at the lower end of space 15.

Reaction chamber 30 is divided into a lower or primary zone 31 and an upper or secondary zone 32 by a refractory throat 33 supported on a throat coil 34. The lower end of primary zone 31 has a refractory floor 36 supported on a coil 37 and having a central slag outlet leading to a slag tank within casing 11. The water wall tubes in primary zone 31 are studded and have a plastic refractory coating 38 applied thereto. Lining 38 may be, in a specific example, /1 inch thick. Burners 40, described more fully hereinafter, are located just below throat 33 and direct the reactants downwardly toward the slag outlet. Just below the burners, water wall 14 is supported by means of brackets 41 resting on framework elements 42 and accessible through closed and sealed hand holes 43.

Coils 34 and 37 are cooled by water circulated under pressure. Above throat 33 supported on coil 34, secondary zone 32 has a refractory block lining 44 which may, in a specific example, be 2 /2 inches thick. Lining 44 terminates in a restricted refractory throat 45 determining the end of the secondary zone and the beginning of the quench zone.

As stated, the reactants undergo a preponderantly exothermic reaction in zone 31 and a preponderantly endothermic reaction in zone 32. It is necessary to rapidly cool the hot product gas leaving zone 32 to prevent any reverse reaction and to stabilize the synthesis gas. This is done by spraying the gas with water from fog nozzles 25 just above the throat 45. The thus cooled product gas flows upwardly through the quench zone 46, Where heat is absorbed by transfer to the bare tubes of water wall 14, and into a hood 47 having an outlet pipe 48. The saturated steam from space 15 is sprayed into this outlet pipe. From pipe 48, the gas flows to a scrubber as described more fully hereinafter.

In a particular example, the product gases leave zone 32 at a temperature of 2300 F. to 2400" F. In zone 46, due to the water spraying, steam is generated which is useful in the subsequent water gas shift. The combined effect of the water quenching and heating eXtrac-- tion in zone 46, plus the introduction of shell blanketing steam into pipe 48, reduces the gas temperature to about 650 P. which is sufiiciently high to avoid condensation in the gas withdrawal line.

The pulverized coal for the process is pre surized by an inert gas such as CO or N. CO is pre erred as it will react with the coal in reactor 15), whereas nitrogen will be a thermal loss even though it would eventually be needed if the final product of the process were am-- monia.

The pulverized coal is delivered from a suitable bini system through a pipe 51 to a hopper having its out-' Referring to FIG. 5, valve 55 comprises a housing 56 having a pair of concentric radially spaced annular valve:

seats 57, 57 separated by an annular recess 58 forming; Seats 57 are engageable by a valve element 60 mounted on an arm 61 pivoted to housing 56' a venting space.

A connection 62 leads to Just prior to complete closure of valve ele at one side of the valve seat. space 58.

ment 60 against seats 57 by valve operator 66, a puff of high pressure gas is applied through connection 62 to vent space 58 to blow adventitious particles of coal from the valve seat. in housing 56 and normally closed by covers 64.

Referring again to FIGS. 1A and 1B, the discharge outlet of valve 55 is connected to a nozzle 67 on the upper end of an upper coal pressure tank 65 having a hopper 68 in its lower end leading to a nozzle 69. This nozzle is connected to a second lock valve 55, identical to lock valve 55, and connected, through an expansion joint 71, to the inlet nozzle 67' of a lower coal pressuretank 65' substantially identical to upper tank 65 except for having a substantially greater capacity, and having a hopper 68 in its lower end leading to a discharge noz-- zle 69.

Discharge nozzle -69 delivers coal from lower tank 65' to a coal feeder 7t) to which the reaction steam requirements are supplied as indicated at 72. A steamcoal line 73 connects feeder to a steam and coal splitter 75 which divides the steam and coal mixture between lines 74 leading to burners 40.

A CO supply receiver 76 supplies high pressure CO to a high pressure puff tank 77 and to an equalizing line 78 interconnecting the coal tank spaces below hoppers 68 and 68. High pressure puff tank 77 is connected by a line 81 to connection 62' for valve 55', and a valved line 82 connects line 81 to connection 62 for valve 55. A valved line 83 connects line 82 to low pressure puff tank 84 which is connected by a valved line 86 to low pressure blowdown receiver 87. As illustrated, low pressure blowdown receiver 87 is interconnected by valved lines to a high pressure blowdown receiver 88, and both receivers are connected to a line 89 communicating with the space in valve 55 below valve element 69 and thus with the upper end of coal pressure tank 65. Adjacent valve 55, lines 82 and 89 are interconnected by a valved cross-connection 91. The pressures above and below the coal in lower coal pressure tank 65 are equalized by a connection 92 extending between the lower part of valve 55 and coal feeder 70.

To assure continuity of the coal supply, the hoppers 50, upper pressure tank 65, lower pressure tank 65', coal feeder 70, and the coal pulverizer (not shown) are provided in duplicate. These are the components Where the maximum wear will be expected, and the capacity of each set is sufiicient to maintain full gas generating capacity during maintenance of its turn set. Normally both feeders 7t operate independently of each other at about half load, feeding coal to the same feed line 73.

Inspection ports 63 are provided (J Splitter '75 divides the steam-coal stream into equal parts each delivered to one of the burners 46.

Upper pressure tank 65 is provided with a level control St) at inlet nozzle 67, and lower pressure tank 65 is provided with a level control 85 at inlet nozzle 67 and a level control 9t) somewhat above hopper 63'.

The sequence of operation of the coal pressurizing or lock hopper system is as follows. Assume that lower pressure tank 65 is at a normal operating pressure (e.g. 460 p.s.i.g.) about 10 p.s.i.g. above the pressure in reactor it] (e.g. 450 p.s.i.g.) to allow a 10 p.s.i.g. pressure drop through the feed lines and burners. Starting with that part of the cycle where upper pressure tank 65 has been pressurized and valves 55 and 55 are closed, when coal in the lower tank 65' drops to the level of control 90, valve 55 opens to discharge the coal in the upper tank into the lower tank. The volume in tank 65' above level control 9b is greater than the entire volume of tank 65 so that, when valve 55' re-closes, it should be clear of coal. The interlock level control 85 prevents closure of valve 55 if coal is not below the level of this level control.

After valve 55 has re-closed, the now empty upper tank 65 is discharged in succession, through line '89 to high pressure and lower pressure blowdown receivers 83 and 8'7, respectively. The blowdown may go through a washer (not shown) and to an inert gas holder (not shown) if ultimate recovery of the inert gas is desired.

Valve 55 is now opened, followed by opening of slide Valve 54. Coal flows from hopper 50 into upper pressure tank 65 until the coal reaches the level of control 8%. At such time, valve 54 is closed first so that valve 55 can be closed clear of coal. Tank 65 is then equalized in succession with the low pressure and high pressure blowdown receivers 88 and 87, respectively, after which tank 65 is pumped up to pressure with the inert gas. As coal is withdrawn from lower pressure tank 65', it will entrain inert gas in its voids. This necessitates putting into tank 65' a volume of gas equal to the volume of the withdrawn coal plus the volume of the voids. The valves used during the described cycle are operated by automatic sequencing controls which may be of a conventional nature.

As stated, the coal from both feeders '70 is delivered to line '73 where it is conveyed by superheated steam to coal-steam splitter 75 which divides the feed stream into equal parts for delivery through lines '74- to the two downfiring burners 4t Referrin more particularly to FIG. 3, each burner 46 comprises a substantially cylindrical barrel 4% mounted coaxially through a flanged sleeve dill, extendim upwardly and outwardly from an opening in casing 111, and a sleeve 4%, of high alloy steel, secured in gas-tight relation in an opening formed by bending the tubes of Wall 14-. A collar 4193 is welded to barrel 4% and bolted to the flange of sleeve 4G1, and inwardly of collar 4-93, a ring 494 is welded to barrel 4% and seats on a spring 4&5 embracing the barrel and seating a sliding ring 4% against the outer end of sleeve 462. Spring 4&5 compensates for any differential expansion between casing 11 and tube wall 14. Anaccess handhole, closed by a cover 407, is provided in sleeve 401.

The reactants are introduced through the burner barrel 44H). However, to avoid flashbacks, the oxygen is not pre-mixed with the coal and steam but is introduced separately through barrel 4%, as by 499A so as to mix with the coal and steam only Within the reaction chamber 30. The burner is water jacketed in a manner not illustrated and, to avoid condensation of the reaction steam at the operating pressure (e.g. 450 p.s.i.g.), circulating saturated water from water wall 14- is used as this wall is at a slightly higher pressure than the operating pressure in reaction chamber 30.

Burners 4t discharge the reactants downwardly toward floor 36 of chamber 39. In this chamber, the gasification reaction is essentially the same as the reaction at atmospheric pressure except for a higher reaction rate due to the superatmospheric pressure. The reactants thus discharged into primary zone 31 undergo a preponderantly exothermic reaction therein with the oxygen rapidly reacting with the coal to form CO and H 0. The gaseous eflluent from primary zone 31, plus any unreacted carbon, fiow through throat 33 into secondary zone 32 where the reaction is preponderantly endothermic with the formation of CO and H The gases leave the secondary zone at 1900 F. to 2800 F. and enter quench zone 46 into which is a fine spray of Water is directed by fog nozzles 25. The steam thus generated directly is useful in the water gas shaft, and this water quenching, plus the introduction of shell blanketing steam into the eflluent gases by means of line 26, brings the temperature of the raw product gases down to about 650 P. which is sufliciently high to avoid condensation in the effluent line 95.

The temperature in primary zone 31 is above the ash fusion temperature of the coal so that a large part of the coal ash may be tapped as molten slag. Due to the fluxing of refractories by molten coal ash, it would be desirable, at least from a maintenance standpoint, to eliminate refractory lining from the water Walls of primary zone 31. An advantage of the invention reactor is that, due to the high superatmospheric operating pressure, the size of the primary zone 31 can be substantially reduced. Hence, the refractory lining can be omitted from this Zone with only a relatively small and inconsequential heat loss to the uninsulated water wall 14.

On the other hand, in secondary zone 32 the ash is not freely molten and hence ash erosion of refractories is much less severe. For this reason, and as it is desirable to conserve the reaction heat, secondary zone 32 has refractory lining on its water wall 14. The resultant saving in oxygen requirements more than equals the expense of renewing the refractory lining 44 at regular intervals.

The molten slag falls through the central slag outlet in floor 36 into a water-filled slag tank or receiver 35 which is constituted by an alloy steel cladding or lining 101 on the inner surface of casing 11 below water wall 14. In addition, a liner 192 is disposed in the slag tank to withstand wear due to granulated slag.

Water is supplied to receiver 35 by means of a spray ring 105, disposed beneath floor 36, and submerged jets (not shown). The level of water in tank 35 is maintained by an overflow pipe 193 discharging to an overflow tank having a side outlet 1% connected by a line 1&9 to the inlet of a water circulating pump 1%. Pump 106 discharges to a line 107 leading to line 10%; extending into and through overflow pipe 103 to spray ring N5. Duplicate strainers ill are arranged in parallel with line 107 and selectively connectible in series therein by means of the illustrated valves. A pump 112 supplies make-up Water to line 137.

The molten slag falling into receiver 35 is solidified and mostly granulated by the water circulating therethrough. Part of the granulated slag is carried away by the overflow water and the remainder is sluiced from the lower end of the slag receiver. Occasional larger pieces of slag are broken up by a cone crusher 113 bolted directly to the bottom nozzle 13 of casing 11. The discharged slag enters a sluice line 114 discharging into upper slag letdown tank 115.

The slag letdown system is essentially a double lock hopper system wherein upper tank 115 continually receives slag sluiced from receiver 35 and the slag is periodically transferred to lower slag letdown tank 115, by gravity and sluicing. In lower tank 115 the slag is depressurized and sluiced to disposal.

Each of the tanks is provided with a lining or cladding 116, 116' on its inner surface, and with a wear liner 117, 117. A pair of circular plug valves 118, 118 and an expansion joint 119 interconnect the tanks, and the outlet of upper tank is controlled by a bell valve 120 operated by a fluid pressure actuator 121. The discharge from lower tank 115' is controlled by a plug valve 122. Tanks 115, 115' are provided with manholes 123, 123.

Ordinarily, valve 118 is open and valve 118 is closed, valve 118 being closed only when it is necessary to inspect or repair valve 118' without interrupting the gasification process. Wear on lower valve 118 can be reduced by closing bell valve 121 to interrupt the slag transfer before closing valve 118'.

It is desirable to maintain the water in slag receiver '35 at a relative cool temperature, such as 100 F. to 150 F., to promote the quenching action, avoid flashing at ulti- "mate slag disposal, and reduce temperature fluctuations in the lower slag let-down tank 115. Most of the sluicing water is re-circulated to save pumping expense, and the heat due to the molten slag is dissipated by blowing down some of the re-ci-rcul'ating water.

A pump 125 (FIG. 1B) circulates the sluicing water. The inlet of this pump receives sluicing water from lines 126, 126 connected to nozzles 127, 127' on the upper portions of letdown tanks 115 and 115, respectively. A line 128 connects the discharge of pump 125 to sluice line 114. A line 131 branching from line 128, discharges sluicing water into liner 117 of tank 115, and a second pump discharges sluicing water through a line 132 into liner 117 of tank 115'.

Overflow tank 110 is provided with a level control 135 mounted through a nozzle 133, and with a surface blow nozzle 134 and a continuous blowdown 136. A blowdown line 137 branches from line 126 connected to nozzle 127 of lower slag letdown tank 115'. When the level of water in overflow tank 110 is above the height of level control 135, this control operates to open blowdown valves 138 and 139 to blowdown water from tanks 110 and 115 respectively. This blows down the water from slag receptacle 35 and also the re-circulated sluice water flowing through tanks 115 and 115' by means of the illustrated interconnections. The systems are replenished with fresh water by pumps 112 and 130'.

The level control 135 of overflow tank 110 provides for proper operation of the overflow connection 103 in slag receiver 35. It also serves to maintain a space above the water in tank 110 to separate from the overflow water the small amount of gas drawn through the slag outlet in floor 33 of the gas generator or reactor. Bleeding of gas through such slag outlet is sometimes necessary to maintain the slag outlet at a sufliciently high temperature. Discharge of such by-pass gas from tank 110 is controlled by a dampered nozzle 140 connected by a line 14-1 to a steam aspirator 142 having a discharge line 143 connected to eflluent line 95 just in advance of scrubber 145.

Gas scrubber 145 is a closed vessel, having a cladding of high alloy steel on its inner surface, and provided with a top gas and vapor inlet nozzle 144. A tube 146 has its upper end seated in nozzle 144 and extends axially downward through the scrubber, and through a grid assembly generally indicated at 150. Grid assembly 150 comprises a grid of apertured troughs 147 supported on a circular ring or transverse supports 148. A bed 151 of 1" Raschig rings is supported on grid assembly 150 and has a packed height of 9'9 in the typical embodiment illustrated, this bed surrounding tube 146 above grid assembly 15%.

A relatively elongated nozzle 152 is detachably secured to nozzle 144 and has a wear liner 153 on its inner surface. Nozzle 152 is connected to gas lines 95 and 143 and supports a spinner 155 disposed in tube 14-6. This spinner is stationary and imparts a cyclonic whirl to the fluids and solids entering the scrubber through nozzles 152 and 144. By removing nozzle 152, spinner 155 may be withdrawn from tube 147 without disturbing the bed of Raschig rings.

Nozzles 154 connected to an annular header 156 spray Water from scrubber 145 into the gas and solids stream in nozzle 152, header 155 being supplied in a manner to be described. The mixture of Water, gas and solids set whirling by spinner 155 passes through a series of radial straightening vanes 157 at the lower end of tube 146 with the water and solids being thrown by centrifugal force into a channeled rim 153 having circumferentially spaced spouts 161 leading downwardly therefrom. The gas flows between spouts 161 and, beneath a battle 162, through scrubber elements 160. The gas then flows upwardly through grid assembly 150 and Raschig ring bed 151 to a clean gas outlet 165.

The separated water and solids flow from spouts 161 into the lower end of scrubber 14.5 which ins an axial let down or blowdown outlet 153% leading from a cornpartrnent 164. formed by baffles 166 and 15'1", baflie 1dr: being apertured as at 158. An outlet 171 is connected to the bottom end of the scrubber outside compartment 154, and is connected to pumps 172 and 173. hum 172 is connected by a line 174 to header 156, and a valve 179 in line 174 is controlled by a level control 175 in the scrubber so as to regulate the amount of water delivered to header 156.

A line 176 connected the outlet of pump 173 to a distributor 177 disposed above the Raschig ring bed 151. A second level control 180 in the scrubber controls a valve in a line 177 connecting outlet 163 to a heat exchanger 17 8. A pump 181 delivers make up water through a valve 182 to heat exchanger 178, and the heated water is delivered by a line 183 to a second heat exchanger 1S4 supplied with saturated steam through a line 136. A line 187 delivers this heated clean water to distributor 177.

In the typical practical embodiment selected for illustration, the raw synthesis gas leaving generator 10 will be almost saturated at 6 50 F. and will carry about 5500 lbs/hr. of solids composed of roughly equal parts of unreacted carbon and fly ash. Scrubber 145 uses the wet method for removing the largest portion of the solids. In order to keep as much vapor as possible in the gas for subsequent shift reaction, the scrubber 14-5 is supplied with water at the saturation temperature of the gas-ap proximately 400 F.

The make-up water from pump 181 is partially heated in heat exchanger 178 by the continuous blowdown from outlet 171 which, after heat extraction therefrom, is discharged to waste. Pump 181 delivers 29,200 lbs/hr. of water at 60 F. to heat exchanger 178, where this water is heated to 215 P. by 15,300 lbs/hr. of blowdown water from outlet 171, which latter is discharged to Waste from heat exchanger 178 at 100 F. The clean make-up water is then further heated to 400 F. in heat exchanger 184 by heat extraction from 750 lbs/hr. of saturated steam at 450 F. supplied by line 186. This 400 F. water is supplied to distributor 177.

The clean make-up water is thus supplied. first to the packed section 151 for washing the relatively clean gas flowing up through this packed section. Economy of water is promoted by this procedure as well as by providing water recirculation for the major part of the water requirements of the packed section. Thus, pump 172 delivers 29,200 lbs/hr. of recirculated water at 400 F. to heater 156 and nozzle 154, and pump 173 delivers 20,700 lbs/hr. of recirculated water at 400 F, to distributor 177. This recirculated Water is relatively clean, as the dirtiest Water is that in compartment 164, which is blown down through outlet 163. The level controls 175 and 180 conjointly operate to maintain the water level in the bottom of scrubber 145 at a reset level through control of valves 170 and 185, respectively.

In the typical practical embodiment selected by way of example, the material balance, for 160x10 s.c.f.d. of synthesis gas (CO-l-H leaving clean gas outlet 165 at 450 p.s.i.g. saturated and 410 F., is represented by the following tables:

Table A Input to gasifier 10 lbs./hr.

Coal at 130 F 27, 700 Reaction steam at 800 F 13, 850 Oxygen (95% pure) at 400 21, 500 Inert gas.-- 1, 390

Total thru burners. 64, 4 10 Equalizing steam at 450 F ,000 Quench spray at 60 F 33, 300

Total input 103, 740

Table B lbs/hr. Outputs Gasifier Scrubber Dry gas 47,000 47, 000 Water vapor in gas 49, 870 63, 770

Total wet gases Unburned carbon overhead Ash overhead Slag tapped Table C Sulphur impurities leaving gasifier 10 (approximate) lbs/hr.

"HUS 164 OS 17 CS0 0. 2 S in overhead residues 58 Table D Percent mol., vol.

Gas Analysis 4 Leaving Leaving Gasifier Scrubber CO -1 20. 7 18.0 Hz"... 16.0 13.9 5. 6 4. 9 54. 9 60.7 2.1 1. 8 1 1 Table E Ultimate percent weight Coal Analysis Raw Coal Pulv. Coal As Re to ceived Gasifier Hardgrove grindability 50 Fineness 40% thru 200 mesh High Htg. value, B.t.u./lb 11,800 12,

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. Apparatus for continuously producing a synthesis gas at a substantial superatmospheric pressure by the reaction at hi h temperatures and substantial superatrnospheric pressure of oxygen and steam with a solid fuel containing carbon; said apparatus comprising, in com bination, an upright scaled pressure vessel; a circular row of water wall tubes with sealed inter-tube spaces forming a sealed reaction chamber within said pressure vessel having a synthesis gas outlet, said tubes being radially inward of the inner surface of the pressure vessel to form therein an annulus space; a steam and water drum in communication with opposite ends of said .tubes to supply water thereto and receive steam therefrom; a connection from the steam space of said drum to the lower end of said annulus space to provide a. pressure-equalizing steam blanket between said water wall tubes and the wall of the pressure vessel; means establishing communication between the upper end of said annulus space and said gas outlet for discharge of steam from said annulus space into the synthesis gas; burner means mounted through said vessel in fiuidatight relation therewith and having a discharge end within said chamber; pressurized means for supplying fuel and steam to said burner means at a pressure in excess of such substantial superatmospheric pressure; and means for supplying an oxygencontaining gas to said reactor adjacent said burner means for reaction therein with the fuel and steam to form the synthesis gas.

2. Apparatus for continuously producing a synthesis gas at a substantial superatmospheric pressure by the reaction at high temperatures and substantial superatmospheric pressure of oxygen and steam with a solid fuel containing carbon; said apparatus comprising, in combination, an upright sealed pressure vessel; a circular row of water wall tubes with sealed inter-tube spaces forming a sealed reaction chamber within said pressure vessel having a synthesis gas outlet, said tubes being radially inward of the inner surface of the pressure vessel to form therein an annulus space; a steam and water drum in communication with opposite ends of said tubes to supply water thereto and receive steam therefrom; a connection from the steam space of said drum to the lower end of said annulus space to provide a pressure-equalizing steam blanket between said water Wall tubes and the wall of the pressure vessel; means establishing communication between the upper end of said annulus space and said gas outlet for discharge of steam from said annulus space into the synthesis gas; a means for supplying said reaction chamber with fuel and steam including a pair of first thermal sleeves each sealed in and extending outwardly from an opening in said tube wall at diametrically opposite locations in the latter; a pair of second thermal sleeves each sealed in an opening in the wall of said pressure vessel and extending outwardly therefrom and each in spaced coaxial alignment with one of said first thermal sleeves; a pair of burner barrels each extending axially through a first and second thermal sleeve in radially spaced relation thereto, and fixed axially relative to the second associated sleeve and movable axially relative to the first associated sleeve; spring means engaged betwee neach barrel and the associated first thermal sleeve and biasing the associated first and second thermal sleeves apart; pressurized means for supplying fuel and steam to said burner barrels for discharge of said fuel and steam into said reaction chamber at a pressure in excess of such substantial superatmospheric pressure; and means for supplying an oxygen-containing gas to said reactor adjacent said fuel burners for reaction therein with the fuel and steam to form the synthesis gas.

3. Apparatus for continuously producing a synthesis gas at a substantial superatmospheric pressure by the reaction at high temperatures and substantial superatmospheric pressure of oxygen and steam with a solid fuel containing carbon; said apparatus comprising, in combination, an upright sealed pressure vessel; a circular row of water wall tubes with sealed inter-tube spaces forming a sealed reaction chamber within said pressure vessel having a synthesis gas outlet, said tubes being radially inward of the inner surface of the pressure vessel to form therein an annulus space; a steam and water drum in communication with opposite ends of said tubes to supply water thereto and receive steam therefrom; a connection from the steam space of said drum to the lower end of said annulus space to provide a pressure-equalizing steam blanket between said Water wall tubes and the wall of the pressure vessel; means establishing communication between the upper end of said annulus space and said gas outlet for discharge of steam from said annulus space into the synthesis gas; 'rneans for supplying said reaction chamber with fuel and steam including a pair of first thermal sleeves each sealed in and extending outwardly from an opening in said tube wall at diametrically opposite locae tions in .the latter; a pair of second thermal sleeves each sealed in an opening in the wall of said pressure vessel and extending outwardly therefrom and each in spaced coaxial alignment with one of said first thermal sleeves; a pair of burner barrels each extending axially through a first and second thermal sleeve, and fixed axially relative to the second associated sleeve and movable axially relative to the first associated sleeve; each burner barrel having a relatively small radial clearance with the associated first sleeve and a relatively large radial clearance with the associated second sleeve; each burner barrel having an annular collar thereon; a spring embracing each burner barrel and engaged between the collar thereon and the outer end or" the associated first sleeve to bias the associated first and second thermal sleeves apart; pressurized means for supplying fuel and steam to said burner barrels at a pressure in excess of such substantial superatmospheric pressure; and means for supplying an oxygencontaining gas to said reaction adjacent said burner barrels for reaction therein with the fuel and steam to form the synthesis gas.

4. Apparatus for continuously producing a synthesis gas at a substantial superatmospheric pressure by the reaction at high temperatures and substantial superatmospheric pressure of oxygen and steam with a solid fuel containing carbon and ash; said apparatus comprising, in combination, an upright sealed pressure vessel; a sealed reaction chamber within said pressure vessel having a synthesis gas outlet at its upper end and a molten ash outlet at its lower end; means for maintaining a fluid pressure-equalizing blanket between said vessel and said chamber; burner means mounted through said vessel in fluidtight relation therewith and having a discharge end Within said chamber; pressurized means for supplying fuel and steam to said burner means at a pressure in excess of such substantial superatmospheric pressure; means for supplying an oxygen-containing gas to said reactor adjacent said burner means for reaction therein with the fuel and steam to form the synthesis gas; means for continuously withdrawing the ash of said fuel from said reaction chamber including an ash receiver within said pressure vessel below said ash outlet to receive molten ash from said reaction chamber, and having a solidified ash outlet through the lower end of said pressure vessel; means supplying water to said ash receiver to chill and solidify molten ash dropping thereinto; an overflow tank communicating with said ash receiver immediately below said molten ash outlet to receive water from said ash receiver and synthesis gas flowing from said reaction chamber through said molten ash outlet; a synthesis gas effiuent line extending from said synthesis gas outlet; and means connecting the space in said overflow tank above the water therein to said efiluent line for flow of synthesis gas from said overflow tank to said effiuent line.

5. Apparatus as claimed in claim 4 including means i2 recirculating water from said overflow tank to said ash receiver.

6. Apparatus for continuously producing a synthesis gas at a substantial superatmospheric pressure by the reaction at high temperatures and substantial superatmospheric pressure of oxygen and steam with a solid fuel containing carbon and ash; said apparatus comprising, incombination, an upright sealed pressure vessel; a sealed reaction chamber within said pressure vessel having a synthesis gas outlet at its upper end and a molten ash outlet a its lower end; means for maintaining a fluid pressure-equalizing blanket between said vessel and said chamber; burner means mounted through said vessel in fluid-tight relation therewith and having to discharge end within said chamber; pressurized means for supplying fuel and steam to said burner means at a pressure in excess of such substantial superatmospheric pressure; means for supplying an oxygen-containing gas to said reactor adjacent said burner means for reaction therein with the fuel and steam to form the synthesis gas; an ash receiverwithin said pressure vessel below said ash outlet to receive molten ash from said reaction chamber, and having a solidified ash outlet through the lower end of said pressure vessel; means supplying water to said ash re ceiver to chill and solidify molten ash dropping thereinto; a first pressure tank having an inlet connected to said solidified ash outlet and having an outlet; a second pressure tank having an inlet connected to the outlet of said first pressure tank, and a sluicing outlet; and valve means selectively operable to isolate said pressure tanks from each other and from said ash receiver for sluicing solidified ash from said sluicing outlet while maintaining such superatmospheric pressure in said reaction chamber and ash receiver.

7. Apparatus as claimed in claim 11 including means recirculating water from said pressure tanks to said ash receiver; and a make-up Water connection to said second pressure tank.

8. Apparatus for continuously producing a synthesis gas at a substantial superatmospheric pressure by the reaction at high temperatures and substantial superatmospheric pressure of oxygen and steam with a solid fuel containing carbon; said apparatus comprising, in combination, an upright sealed pressure vessel; a sealed reaction chamber within said pressure vessel having a synthesis gas outlet; means for maintaining a fluid pressure-equalizing blanket between said vessel and said chamber; burner means mounted through said vessel in fluid-tight relation therewith and having a discharge end within said chamber; pressurized means for supplying fuel and steam to said burner means at a pressure in excess of such substantial superatmospheric pressure; means for supplying an oxygen-containing gas to said reactor adjacent the discharge end of said burner means for reaction therein with the fuel and steam to form the synthesis gas; means for injecting water into said reaction chamber above said burner means; a synthesis gas efiluent line extending from said synthesis gas outlet; and means for cooling the synthesis gas by mixing steam therewith adjacent said synthesis gas outlet.

References Cited in the file of this patent UNITED STATES PATENTS 2,650,160 Totzek Aug. 25, 1953 2,662,007 Dickinson Dec. 8, 1953 2,701,755 Strausser Feb. 8, 1955 2,801,158 Grossman July 20, 1957 2,851,346 Sprague Sept. 9, 1958 2,871,114 Eastman Jan. 27, 1959 FOREIGN PATENTS 769,829 Great Britain Mar. 13, 1957 

1. APPARATUS FOR CONTINUOUSLY PRODUCING A SYNTHESIS GAS AT A SUBSTANTIAL SUPERATMOSPHERIC PRESSURE BY THE REACTION AT HIGH TEMPERATURES AND SUBSTANTIAL SUPERATMOSPHERIC PRESSURE OF OXYGEN AND STEAM WITH A SOLID FUEL CONTAINING CARBON; SAID APPARATUS COMPRISING, IN COMBINATION, AN UPRIGHT SEALED PRESSURE VESSEL; A CIRCULAR ROW OF WATER WALL TUBES WITH SEALED INTER-TUBE SPACES FORMING A SEALED REACTION CHAMBER WITHIN SAID PRESSURE VESSEL HAVING A SYNTHESIS GAS OUTLET, SAID TUBES BEING RADIALLY INWARD OF THE INNER SURFACE OF THE PRESSURE VESSEL TO FORM THEREIN AN ANNULUS SPACE; A STEAM AND WATER DRUM IN COMMUNICATION WITH OPPOSITE ENDS OF SAID TUBES TO SUPPLY WATER THERETO AND RECEIVE STEAM THEREFROM; A CONNECTION FROM THE STEAM SPACE OF SAID DRUM TO THE LOWER END OF SAID ANNULUS SPACE TO PROVIDE A PRESSURE-EQUALIZING STEAM BLANKET BETWEEN SAID WATER WALL TUBES AND THE WALL OF THE PRESSURE VESSEL; MEANS ESTABLISHING COM- 